1. Field
The technology described herein relates to optical imaging structures and methods.
2. Related Art
Solid state image sensors, often referred to as “imagers,” detect incident radiation and produce, or provide, an image based on the detected radiation. A typical imager comprises a two-dimensional array (referred to as a focal plane array, or an imaging array) of pixels each comprising a photodetector, in combination with a readout integrated circuit (ROIC). The photodetectors are sensitive to (i.e., detect) incoming radiation and produce an output signal (referred to as a “photoresponse”) based on the detected radiation. The ROIC scans and quantitatively evaluates the outputs from the photodetectors, and processes them to create an image. Imagers are useful in various applications, such as professional and consumer video, still image photography, remote surveillance, astronomy, machine vision, and others.
FIG. 1A illustrates a cross-sectional view of a conventional CMOS pixel of a conventional imager. The pixel 100 includes substrate 110, an insulating layer 112, a photodetector 114, and a backend layer 116 formed on the insulating layer 112.
Conventional imager pixels each include a single detecting element, i.e., photodetector 114. As illustrated in FIGS. 1A and 1B (which is a top-down view of pixel 100 taken along the line A-A′, illustrating the placement of photodetector 114 within the insulating layer 112), the photodetector 114 does not fill the entire pixel 100. Rather, the sides of the photodetector 114 are shorter than the sides of the pixel WP by an amount 2L (an amount L on either side of the photodetector 114). In some conventional CMOS pixels, the detecting element (i.e., photodetector 114) is formed in the substrate 110 itself.